This specification relates to additive manufacturing, such as fused filament fabrication (FFF) three dimensional (3D) printing.
FFF using extruded polymer filament is employed for manufacturing three dimensional objects. Current FFF printing is typically accomplished by forcing a solid plastic feedstock through a heated nozzle. The filament is liquefied before or as it passes through the constriction in the nozzle, and the feed pressure causes material to be extruded to form a beam of material added, layer by layer, to build the object. 3D models of objects can be designed using computer-aided design (CAD) software and then converted to toolpaths for the nozzle of a 3D extrusion printer, either by the CAD software or separate software, often referred to as a slicer.
In addition, when the toolpaths specify long runs of FFF extruded filament, this can result in warped parts as the liquefied extrusion material cools and solidifies. Specifically, warp is most pronounced at convex corners of the part's first few layers. This problem of warped parts becomes even more pronounced as parts increase in size beyond standard consumer FFF 3D printers. Current techniques for warp prevention with FFF 3D printing include the creation of rafts, such as described in U.S. Patent Pub. No. 2014/0371895, and the ad hoc addition of extra extrusion material around the part being 3D printed to help hold down the first few layers.